Fiber pulping device, method for pulping plant material, method for producing a semi-finished product and use of plant material for the production of paper, cardboard or carton

Abstract

Fiber digestion device (1) for digesting plant material by means of steam pressure digestion, the device comprising a press and drain chamber (2), a press channel (3), at least one first heating tube (4), and a pressure relief tank (6), wherein a pressure plate (9) for compacting and dewatering the plant material and for determining a material flow in the fiber extraction device (1) is assigned to the pressing and dewatering chamber (2), wherein the pressing and dewatering chamber (2) is further connected with a feeding device (7) for feeding the plant material to be processed, wherein the pressing and dewatering chamber (2), the pressing channel (3), the at least one first heating tube (4), and the pressure relief tank (6) are connected to each other in such a way that plant material introduced into the pressing and dewatering chamber (2) by the feeding device (7) is first moved into the pressing channel (3) by a movement of the pressure plate (9) and then passes through the at least first heating tube (4) in order to then enter the pressure relief tank (6).

Description

Technical field

[0001] The invention relates to a fiber extraction device, a method for extraction of plant material, a method for producing a semi-finished product and a use of plant material for the production of paper, cardboard or carton according to the independent claims. State of the art

[0002] Methods and devices for fiber disruption are known and commonly used. Steam explosion disruption was already described at the beginning of the twentieth century, for example in US 1,578,609. It is based on first subjecting plant material to high pressure and heating it, and then suddenly reducing the pressure, which causes an explosive vaporization of the water. This vaporization of the water results in the fiber disruption.

[0003] Furthermore, CN 1 01 463 570 A is known from the prior art, which discloses a device comprising a screw for processing plant fibers and a steam pressure digestion.

[0004] Furthermore, DE 635 823 A is known, which discloses a feeding device for containers for the continuous production of fibrous material with a feeding channel connected to the treatment container and a piston moving back and forth for producing a fibrous material plug. Object of the invention

[0005] The object of the present invention is to overcome the disadvantages of the prior art. Solution to the task

[0006] The subject matter of the independent patent claims leads to the solution of the problem. Advantageous embodiments are described in the dependent patent claims.

[0007] According to the present invention, a fiber pulping device for processing plant material by means of steam pressure pulping comprises a pressing and dewatering chamber, a pressing channel, at least one first heating tube, and a pressure relief vessel. The aforementioned components can be configured as interconnected zones of a fiber pulping device. The phrase "at least one first heating tube" specifically means that a second heating tube may optionally be included.

[0008] The aforementioned components can each have a circular cross-section. Preferably, they are arranged coaxially to each other, thus sharing a common (imaginary) central longitudinal axis. Preferably, the press and drainage chamber, the press channel, and all existing heating pipes have a cylindrical shape.

[0009] The pressing and dewatering chamber is equipped with a pressure plate for compacting and dewatering the plant material and for determining the material flow in the fiber pulping device. The pressure plate is preferably configured to convey the plant material to be pulped into the pressing channel after it has been introduced into the pressing and dewatering chamber.

[0010] The pressure plate is preferably driven by a hydraulic cylinder. The pressure plate and the press and drain chamber can interact in the manner of a piston engine, with the pressure plate acting as the piston and the press and drain chamber as the cylinder. The outer diameter of the pressure plate—preferably round in cross-section—can correspond to the inner diameter of the press and drain chamber such that the former is only slightly smaller than the latter. However, the tightness between piston and cylinder required in reciprocating engines such as diesel or gasoline engines is not necessary. The escape of fluid through a remaining gap between the pressure plate and the press and drain chamber is usually unproblematic and sometimes even desirable, as described in more detail below.

[0011] Conveying and thus moving the plant material through the press and dewatering chamber, essentially by pushing it through the pressure plate, advantageously results in only a minimal generation of fines. This is particularly beneficial if the plant material is to be used for papermaking after steam pulping, for example, as a high proportion of fines negatively impacts paper quality. The screw conveyors frequently used in the prior art often produce an undesirably high proportion of fines due to the higher friction and shear between the plant material and the components of the screw shaft and the screw conveyor housing.

[0012] The fiber digestion device can comprise a single pressure plate that facilitates the flow of plant material. The pressure plate can be the sole component that mechanically effects this material flow. Furthermore, while a pressure drop upon entering the depressurization chamber, as described in more detail below, can also induce material flow, this does not occur mechanically, i.e., without components that mechanically move the plant material.

[0013] When the material flow is mentioned above and below, this preferably refers to the material flow of plant material already located in the pressing and dewatering chamber, which is conveyed or moved to the pressure relief container.

[0014] Preferably, in addition to dewatering, a certain degree of compaction of the plant material takes place in the pressing and dewatering chamber. However, the formation of the densest possible plug preferably occurs only in the pressing channel described below. Besides the obvious increase in the dry matter content of the plant material, the dewatering process can also carry away fine particles, which are thus removed from the plant material along with the discharged water or, more generally, the discharged aqueous liquid before the actual pulping.

[0015] The pressing and dewatering chamber is further equipped with a feeding device for the plant material to be processed. Feeding, i.e., introducing the plant material into the pressing and dewatering chamber, can be accomplished in various ways. In the simplest case, the pressing and dewatering chamber includes an opening serving as a feeding device, through which the plant material is fed by means of a device located upstream of the fiber processing unit. Feeding can be effected primarily by gravity. Preferably, however, a screw conveyor is associated with the pressing and dewatering chamber. Unlike a plug screw, a screw conveyor can introduce the plant material to be processed into the pressing and dewatering chamber with minimal friction. Preferably, the screw conveyor is arranged such that the direction of gravity and the conveying direction of the screw conveyor coincide.Preferably, the fiber digestion device comprises exactly one single feeding device, particularly preferably in the form of a screw conveyor.

[0016] At least one section of the press and drain chamber may have perforations. Within the scope of the present invention, a perforation preferably refers to a plurality of adjacent bores or, more generally, adjacent holes that allow a fluid to exit the press and drain chamber.

[0017] These can be boreholes of different shapes and sizes. Preferably, the shape and size of the boreholes forming the perforation are chosen so that liquid can escape, but plant material is largely prevented from passing through.

[0018] The perforation can be surrounded by a baffle plate. On the one hand, the baffle plate can prevent any liquid escaping from the perforations, and potentially splashing out, from posing a danger to operators. On the other hand, the baffle plate can also serve to collect and divert the liquid escaping from the perforations. The considerations outlined above for liquids also apply to the release of steam – which would only occur in an emergency – and which will be explained below.

[0019] Should overpressure occur in the heating tube(s), which, for example, cannot be reduced by the safety valves, rupture discs, and similar devices in the heating tube and expansion tank (described below) due to a blockage, the plug in the press channel may burst. This bursting causes the pressure previously built up in the heating tubes and, if applicable, in the expansion tank, or the high-pressure steam, to escape through the press channel into the press and drain chamber, and from there through the perforation or, for example, through the gap between the press and drain chamber housing and the pressure plate, as described below. While this is undesirable during normal operation, it provides protection against even more serious machine and / or personal damage. A baffle plate is also advisable in this case, where steam escapes through the perforation.

[0020] Alternatively or in addition to the perforation in the housing of the press and drain chamber described above, drainage can be achieved in another way, for example via perforation in the pressure plate or via the aforementioned gap between the pressure plate and the inner wall of the housing of the press and drain chamber. This gap, at least when used for drainage, is not sealed against the inner wall of the housing by a ring seal or similar device.

[0021] The pressing and dewatering chamber essentially functions as a pressing chamber. This means that dewatering can only occur to a limited extent, and the focus is on compressing the plant material to form the plug in the subsequent pressing channel. Furthermore, it should be noted that the degree of dewatering always depends on the dry matter content of the plant material. If the plant material already has a very high dry matter content when introduced into the pressing and dewatering chamber, significant dewatering may not occur in some cases. Since, depending on the plant material used and especially its dry matter content, at least some dewatering will usually take place, it is always referred to as a pressing and dewatering chamber, and not simply a pressing chamber.

[0022] The pressing and dewatering chamber, the pressing channel, the first heating tube, and the pressure relief tank are connected in such a way that plant material introduced into the pressing and dewatering chamber by the feeding device first enters the pressing channel by a movement of the pressure plate and then passes through the first heating tube before entering the pressure relief tank.

[0023] In the direction of material flow, the press and dewatering chamber is preferably followed first by the press channel, then at least a first heating pipe and then the pressure relief tank.

[0024] Heat transfer from the at least one heating tube to the plant material preferably occurs through conduction between the surfaces of the at least one heating tube and / or a heating element located within the heating tube and the plant material in contact with these surfaces or this heating element. Alternatively or additionally, heat transfer to the plant material by convection or thermal radiation is also possible. For example, in addition to or as an alternative to the heating tube inserts and heating pads described below, it is also possible to introduce hot steam into the heating tube via a suitable device to heat the plant material located there.

[0025] A backflow prevention device can be installed in the press channel. Any means suitable for preventing the material in the press channel from moving against the direction of material flow can be considered a backflow prevention device. The direction of material flow in the press channel is determined by the pressure plate, which compresses the plant material into a plug. The flow thus runs from the pressing and dewatering chamber to the expansion tank. Pressure acting on the plug, resulting from an increase in temperature and consequently pressure in at least one heating tube, exerts a force opposite to the direction of material flow. The backflow prevention device ensures that this force does not move the plug against the direction of material flow.

[0026] A wide variety of devices can be used to prevent backflow. For example, targeted constrictions can be introduced into the press channel. Any type of constriction of the press channel's clear cross-section can act—at least to some extent—as a backflow preventer. Furthermore, barbed elements can be considered. Numerous other alternatives are conceivable. For instance, elements acting like a one-way barrier could be used. Backflow preventers with a sliding surface that allows material flow in one direction and a stop surface that prevents reverse material flow are also possible.Preferably, the sliding surface is inclined in cross-section at an angle of less than 60°, more preferably less than 45°, and optionally even less than 30° to the material flow direction to allow the plant material to slide along it. The stop surface is preferably arranged substantially orthogonally to the material flow direction. Preferably, the stop surface follows the sliding surface in the material flow direction.

[0027] To ensure a stable plug is formed, the press channel must have a certain length. It is quite possible that the plug will not be homogeneous along its entire length. For example, the plug may only be considered stable, and particularly steam- and pressure-tight, in the middle or near the end of the press channel facing the heating pipe(s). At the opposite end of the press channel, immediately following the press and dewatering chamber, the plug may be less stable. To prevent the plant material forming the plug from moving back into the press and dewatering chamber, an additional shut-off device, such as a second slide valve, may be considered, which will be explained in more detail below.

[0028] The press channel can, for example, have a length between one and three meters, such as approximately or exactly two meters. The length of the press channel required to form a tight plug can depend on the cross-section of the press channel, the plant material used, and other parameters. Depending on these parameters, designs without a backflow prevention device are conceivable. Thus, depending on factors such as the plant material used and the length and diameter of the press channel, a tight plug can be formed even without a backflow prevention device. Whether this is possible can be determined, for example, through preliminary tests.

[0029] Regarding the length and diameter of the press channel, a length-to-diameter ratio (L / D ratio) between 3:1 and 8:1, preferably between 4:1 and 6:1, and particularly preferably of approximately or exactly 5:1, can be considered.

[0030] The aforementioned backflow prevention device also acts to a certain extent as a damming device against the movement of plant material in the direction of material flow. Thus, during the filling of the press channel by the movement of the pressure plate, it counteracts this filling process to a certain degree. This function as a damming device makes it more difficult to introduce the plant material due to the movement of the pressure plate. This, in turn, contributes to dewatering, as the presence of the backflow prevention device, acting as a damming device, compresses the plant material more strongly—and thus dewaters it—within the press and dewatering chamber.

[0031] Alternatively or additionally to the backflow prevention device, a backflow preventer can be installed in the press channel that does not perform a backflow prevention function. This can be achieved simply by the mounting location of the backflow preventer: If it is mounted in the rear section of the press channel near the transition to the first heating pipe, it cannot perform a backflow prevention function with respect to the plug. The backflow preventer can be a constriction or any device that serves as a "narrowing" of the press channel's clear cross-section.

[0032] Such a damming device in the rear area of ​​the press channel near the transition to the first heating pipe, which can also be mounted directly at the end of the press channel, is therefore conceivable as an alternative or in addition to those described above.

[0033] If present, the backflow prevention device and / or the backflow prevention device can be static, meaning they are not adjustable or otherwise modifiable. The device serving as a backflow prevention device and / or backflow prevention device can, for example, be bolted, welded, or otherwise permanently connected to the housing of the press channel.

[0034] Alternatively, consideration could be given to making the backflow prevention device and / or the backflow prevention device adjustable. For example, barbed elements or barriers could be adjustable to the press channel by means of threads or in another suitable manner, so that their penetration depth into the press channel and / or their orientation within the press channel could be adjusted.

[0035] The fiber slitting device can include a second heating tube between the first heating tube and the expansion vessel, wherein the internal diameter of the second heating tube is larger than the internal diameter of the first heating tube. The internal diameter of the second heating tube can be, for example, between 40 and 60%, preferably approximately or exactly 50%, larger than the internal diameter of the first heating tube. The internal diameter is preferably the free cross-section of the respective heating tube.

[0036] The two heating pipes can also be designed as differently shaped sections of a single heating pipe.

[0037] The interior of the first heating pipe, or, if present, a shared interior of both heating pipes, may only be connected to the press channel on one side and to the expansion tank on the other. It is therefore conceivable that the interior should not include any further openings that would allow pressure equalization or material flow. Alternatively, it may be considered to equip one of the heating pipes, preferably the second heating pipe if present, with a pressure relief valve, a rupture disc, a combination of a rupture disc and a downstream pressure relief valve, or a similar device, in order to provide controlled pressure relief in the event of an undesired pressure increase.

[0038] Due to the conservation of mass and the strong compression of the plant material already present in the press channel and subsequently in the first heating tube, the larger internal diameter of the second heating tube results in a lower fill level compared to the first heating tube. Preferably, the first heating tube typically has a fill level of at least approximately 100%, while the second heating tube may, for example, have a fill level of 60 to 80%.

[0039] The fill level of the press channel is also preferably 100% during operation. "During operation" here preferably means a continuous operating mode of the fiber processing device, whereby the plug in the press channel has already been installed, and plant material has already entered the expansion tank via an outlet connecting the heating pipes to the expansion tank.

[0040] If a second heating tube is present, it is, as already mentioned above, not usually 100% full during operation. This is because it has a larger internal diameter than the first heating tube and regularly releases plant material into the expansion chamber via the outlet. Often, a gradient in fill level develops in the second heating tube, with the fill level decreasing towards the outlet when measured against a cross-sectional area of ​​the second heating tube perpendicular to its central longitudinal axis.

[0041] A grid can be arranged within the aforementioned outlet or within the expansion chamber to shred the plant material entering the expansion chamber. Shredding occurs through impact on the grid. Alternatively, any shredding device, preferably passive, can be used, for example, statically arranged blades or the like.

[0042] The internal diameter of the first heating tube can be slightly smaller, for example, about two to seven percent, preferably about five percent, than the internal diameter of the press channel. This creates a build-up at the outlet of the press channel, where the plant material enters the first heating tube, thus increasing the pressing pressure. This build-up occurs in addition to the plugging and compression within the press channel, which causes the plug to form. However, it is also possible for the internal diameter of the first heating tube to essentially correspond to the internal diameter of the press channel, since in other embodiments the press channel can independently cause the plug to form. This can be achieved, for example, by the backflow prevention device or a previously described damming device.However, it is also possible that the clear dimension of the first heating pipe is smaller than the clear dimension of the press channel in the manner described above, the press channel additionally including a backflow prevention device and / or a damming device.

[0043] A shut-off device may be provided at the transition between the second heating tube and the expansion vessel. This could, for example, be a gate valve. If the fiber digestion device comprises only a single (first) heating tube, the shut-off device may also be located between this tube and the expansion vessel. The shut-off device can open depending on the pressure to allow steam digestion. In the closed position, the shut-off device allows pressure to build up in the heating tube(s), which are sealed at the other end by the plug.

[0044] As an alternative to pressure-dependent opening, the shut-off device can also be opened at regular intervals. In this operating mode, opening is time-dependent rather than pressure-dependent. It can be configured that if a pressure in the second heating pipe exceeds a safety-critical threshold, the shut-off device will open even before the time after which it would normally open.

[0045] An additional shut-off device, for example in the form of a second gate valve, can be arranged between the pressing and dewatering chamber and the pressing channel. This optional additional shut-off device can increase safety, particularly in the event that the pressure in one of the heating tubes rises sharply and escapes against the material flow direction through the pressing channel towards the pressing and dewatering chamber, causing the plug in the pressing channel to burst. If such a plug rupture occurs, an additional shut-off device can prevent damage to property and personal injury. Depending on the process flow of the fiber pulping unit, the opening and closing of the additional shut-off device may be dependent on the movement of the pressure plate.

[0046] Further advantages and the operation of the second valve or, in general, the further shut-off device are explained below with reference to the inventive method.

[0047] It is conceivable that one of the heating pipes, for example, the second heating pipe, has a pressure relief valve. Preferably, only the second heating pipe has at least one pressure relief valve. During normal operation, such a pressure relief valve does not affect the pressure prevailing in the heating pipe(s). It is only activated in an emergency, when a predetermined pressure is deemed too high. Even with heating pipes equipped with a pressure relief valve, the only openings available for pressure equalization and material flow during normal operation are the opening between the heating pipe and the press channel, and the transition between the heating pipe and the expansion tank.

[0048] Thermal insulation can be provided between the casing of the press channel and the casing of the first heating tube. This insulation does not impede the entry of plant material into the heating tube; it merely insulates the casings or casing sections from each other. The insulation is intended to minimize the transfer of heat energy from the first heating tube to the press channel.

[0049] The feeding device can be a screw conveyor. Preferably, the screw conveyor is arranged such that its conveying direction essentially corresponds to the direction of gravity.

[0050] Heating within the heating pipes is preferably achieved via heating pads assigned to the respective housing of the heating pipe, which heat it from the outside. Alternatively, or preferably additionally, a heating pipe insert arranged inside the heating pipe can be considered, through which thermal oil flows, and which also heats the material inside the heating pipe. The heating pipe insert can, for example, comprise a heating conductor with, for instance, four cross-shaped supports.

[0051] The brackets do not have to be cross-shaped, and a different number of brackets may be used.

[0052] Furthermore, consideration may be given to using only heating pads or only one - or several - heating pipe inserts for heating.

[0053] Instead of heating pads, alternative heating devices can be used to heat the casing of the heating tube(s). For example, the casing of the heating tube can include bores through which thermal oil flows. Furthermore, pipe trace heating, heating tapes, or similar devices can be used. The casing of the heating tube can also be double-walled, with a heating device or thermal oil flowing between an outer wall, which separates the heating tube from the outside, and an inner wall, which defines an interior space for the plant material entering.

[0054] Alternatively or in addition to the heating pads and the heating tube insert, as mentioned above, it may be possible to introduce hot steam into at least one of the heating tubes to heat the plant material.

[0055] The variants of the aforementioned fiber processing device can be stationary and installed, for example, in a hall or similar structure. Alternatively, the fiber processing device can be installed in a container or similar container for mobile use. Depending on the harvest time of the plant providing the plant material, the mobile fiber processing device can then be transported directly to a field to be harvested. It is usually more economical to bring the fiber processing device to where the plant material is produced (especially through harvesting) than to transport large quantities of harvested plant material to a distant, stationary fiber processing device.

[0056] A solid-liquid separation device may be arranged within the relaxation container.

[0057] It may also be considered to provide a solid-liquid separation device that replaces the relaxation vessel and performs both its function and the solid-liquid separation.

[0058] The solid-liquid separation device could be a press. Alternatively, any solid-liquid separation device, particularly mechanical ones, could be used. For example, the principles of centrifugation, filtration, or classification could be employed. Numerous other alternatives are conceivable.

[0059] The aforementioned solid-liquid separation device, which is located within or replaces the expansion vessel, can remove at least some of the lignin after pulping. Such lignin separation is particularly successful if, through appropriate process and especially temperature control, the plant material—and thus also the lignin—exhibits a temperature in the expansion vessel after steam pressure pulping that allows for mechanical separation of the lignin. Although lignin, as an amorphous polymer, does not typically melt like low-molecular-weight substances, it can be separated from the other components of the plant material by a solid-liquid separation device, especially at temperatures above its glass transition temperature.Preferably, the process control, and in particular the temperature control, ensures that the plant material in the relaxation chamber still has a temperature above 125°C, preferably above 130°C. It is also conceivable that the plant material in the relaxation chamber still has a temperature above 140°C, or even above 155°C, or above 170°C, or above 190°C.

[0060] If the plant material contains lignin, which has a melting point due to its composition, then the above and following considerations regarding the glass transition temperature apply analogously.

[0061] In addition to removing at least some of the lignin, the solid-liquid separation unit in the relaxation tank can also remove at least some of the remaining water, thus increasing the dry matter content of the processed plant material. This, in turn, can have a positive effect on shelf life and other properties. Furthermore, the aforementioned solid-liquid separation unit can also remove any fine particles along with the lignin and / or water. For example, the plant material might have a dry matter content of between 28% and 40% (e.g., approximately 35%) before entering the relaxation tank, and a dry matter content of over 50% (e.g., approximately 60%) after processing and passing through the solid-liquid separation unit.

[0062] The discharged fines, which are separated from the plant material by dewatering before entering the press channel and by the solid-liquid separation described above, can be used, for example, to feed a biogas plant.

[0063] In addition to the fiber pulping apparatus described above, the present invention also comprises a method for pulping plant material by means of steam pressure pulping using a variant of the apparatus described above. Details explained above with regard to the apparatus apply equally to the method and vice versa.

[0064] The variations of the process described in more detail below provide high-quality plant material which can be further processed, for example, for papermaking in a pulper and subsequently in a refiner without elaborate pretreatments.

[0065] The plant material to be processed can be herbaceous plant material. A herbaceous plant is a plant that is essentially non-lignified, i.e., exhibits essentially no secondary thickening. Particularly preferably, the above-ground parts of the herbaceous plant are processed within the scope of the present invention.

[0066] Particularly preferred within the scope of the present invention are the following plants: the plant genus Miscanthus (genus within the grass family), the plant species Silphium perfoliatum (cup plant), the plant genus hemp (genus within the cannabaceae family), the plant genus stinging nettle (genus within the nettle family), the plant genus banana (genus within the banana family), particularly the species "dessert banana", the plant genus lavender (genus within the mint family), particularly the species "true lavender", or the plant genus hops (genus within the cannabaceae family). Furthermore, straw can be used as plant material, preferably threshed and dry stalks and leaves of cereals, oilseed crops, fiber crops, or legumes. Cereal straw is particularly preferred. In the context of the present invention, steam pressure digestion is understood to be a physical process for fiber digestion. Generally, in steam pressure digestion, the plant material is exposed to heat and high pressure in a suitable vessel, after which the pressure is rapidly reduced by opening a valve or the like. Due to the pressure drop, the water in the plant material boils explosively, thereby rupturing the cell structures.

[0067] In this process, the plant material is fed into the press and dewatering chamber via the feeding device and subsequently compacted and preferably at least partially dewatered by the movement of the pressure plate within the chamber. "Partial" dewatering, as defined here, refers to an incomplete solid-liquid separation. After dewatering, the plant material still contains a certain amount of water; its dry matter content is therefore not 100%, and is typically significantly lower. The dry matter content after dewatering, i.e., in the press channel, in the heating tube(s), and immediately before entering the expansion chamber, can be, for example, between 20% and 40%, preferably between 28% and 40%, and more preferably around 35%.

[0068] The movement of the pressure plate is preferably a reciprocating, i.e., periodic and therefore intermittent, motion, as known from piston engines. Since the pressure plate causes the movement of the plant material in the direction of material flow, and no screw conveyor is used for this purpose, the formation of fine particles is avoided.

[0069] The plant material is then introduced into the press channel by the movement of the pressure plate and pressed there into a plug.

[0070] The plug preferably serves as a pressure- and vapor-tight barrier, sealing the downstream heating tube at one end. The plug preferably builds up continuously at one end section of the press channel facing the press and dewatering chamber through material feed from the pressure plate. Simultaneously, the plug preferably builds up continuously at an opposite end section of the press channel through the conveyance of plant material into the heating tube. Preferably, a dynamic equilibrium exists between build-up and breakdown, i.e., the amount of material entering at one end corresponds, at least averaged over appropriately selected time periods, to the amount of material exiting at the other end.The feeding device can be operated in such a way that the quantity of plant material fed in a given period of time essentially corresponds to the quantity of plant material that is introduced into or removed from the relaxation container during the same period of time.

[0071] Preferably, a plug is formed in the press channel which requires no further counter-pressure to be stable. The formation of the plug preferably results solely from the compression of the material in the specially designed press channel.

[0072] The plant material, leaving the press channel, is then conveyed into at least one first heating tube and heated there, leading to a pressure increase in the at least one first heating tube. This pressure increase preferably occurs because the water content of the plant material heats up and partially evaporates, and because the pressure cannot escape from the heating tube(s) due to the plug in the press channel and the closed shut-off device.

[0073] The plant material, exiting at least one heating tube, then enters the expansion chamber, where the pressure is lower than that of the first heating tube. During this process, the plant material is broken down. Preferably, the aforementioned shut-off device, in particular the slide valve, located between the expansion chamber and the heating tube immediately upstream of it (especially in an outlet), opens in response to pressure. This ensures that the pressure change resulting in the breakdown occurs abruptly.

[0074] The transition to the expansion vessel can be located between this vessel and the first heating tube, or between this vessel and the second heating tube, depending on whether a second heating tube is present. Digestion preferably occurs through the explosive vaporization of the water content in the plant material mixture, which evaporates rapidly due to the lower pressure in the expansion vessel compared to the heating tube.

[0075] It can be envisioned that the direction of material flow of the plant material within the fiber pulping device, between the pressing and dewatering chamber and the end of the first heating tube, is determined solely by the pressure plate after the plant material has been introduced by the feeding device. The pressure plate can therefore be the only element between the pressing and dewatering chamber and the end of the first heating tube that actively effects material flow. Other movements of the plant material preferably occur only during its introduction into the pressing and dewatering chamber by the feeding device and due to the high pressure differential at the transition to the expansion chamber. There, the plant material can be drawn from the upstream first or second heating tube into the expansion chamber by a suction effect.

[0076] If the material flow direction is determined solely by the pressure plate, as described above, this can reduce the formation of fine particles, in contrast to a situation where a screw conveyor determines the material flow direction.

[0077] The direction along which the plant material is introduced from the feeding device into the pressing and dewatering chamber does not define the aforementioned material flow direction.

[0078] It is conceivable that the aforementioned process operates continuously. However, neither the feeding of the plant material nor its conveying in the direction of material flow through the pressure plate needs to be continuous in the sense that the exact same material flow is observed in every arbitrarily small unit of time, for example, into the pressing and dewatering chamber and out of the heating tube towards the expansion tank. An intermittent, i.e., pulsating, movement is also conceivable, both with regard to the feeding process and the conveying and transfer into the expansion tank. This applies, on the one hand, to the pressure plate, which—similar to a piston engine—typically performs such a pulsating movement, and on the other hand, to the transfer of the plant material into the expansion tank, which is usually pressure- or time-dependent and therefore also intermittent.

[0079] A continuous process is preferably present when, over periods of time that can range from a few minutes to several hours, the mass of the plant material introduced into the pressing and dewatering chamber essentially corresponds to the mass of the plant material that enters the defrosting container.

[0080] It can be assumed that the temperature inside the at least one first heating tube is at least 125°C, preferably at least 130°C, and / or that the dry matter content of the plant material immediately before entering the expansion chamber is between 28 and 40%.

[0081] If a second heating pipe is present, the aforementioned temperature of at least 125°C or 130°C is preferably found in the second heating pipe. The temperature in the first and especially in the second heating pipe can reach up to 260°C.

[0082] The crucial factor is that the temperature is still present in the evaporation tank, where, according to a preferred embodiment of the process, the lignin is separated by a solid-liquid separation, for example by means of a press.

[0083] The glass transition temperature of lignin is typically above 125°C, and sometimes even above 130°C. This was already described above in relation to the fiber digestion device.

[0084] With a dry matter content significantly below 28%, plug formation in the press channel may be insufficient. However, this also depends on the design of the press channel (length, backflow prevention device, and damming device) and the plant material used.

[0085] With a dry matter content significantly exceeding 40%, it can sometimes happen that the steam pressure digestion in the expansion vessel is insufficient, meaning that an unacceptably high proportion of the plant material is not digested or is only insufficiently digested. However, this also depends on the plant material used and the process parameters, such as the pressures and temperatures in the expansion vessel and the upstream heating tube(s).

[0086] A suitable dry matter content and advantageous process parameters can be determined in preliminary trials. As already described, temperatures between 125°C and 260°C are possible. Furthermore, the maximum pressure reached during the process can be between 3 bar and 50 bar, preferably between 5 bar and 50 bar, more preferably between 6 bar and 50 bar, and even more preferably between 6 bar and 40 bar, for example, around 7 bar. Significantly higher pressures of, for example, 20 bar or 30 bar are also conceivable. The residence time of the plant material before the actual steam pulping by pressure reduction in the fiber pulping device can be between approximately 30 seconds and 60 minutes, preferably in the range of 1 minute to 30 minutes. To enable the actual steam pulping by sudden pressure reduction, the pressure can be lowered to atmospheric pressure.It may also be considered to reduce the pressure to a value above atmospheric pressure, provided that it is still significantly below the pressure to which the plant material was previously subjected.

[0087] It is conceivable that the shut-off device opens depending on the pressure prevailing in at least one heating tube. The shut-off device, for example, the valve connecting the first heating tube or, if present, the second heating tube to the expansion chamber, can open, for instance, when a predetermined pressure is reached. This opening causes a flow of some of the plant material from the first or second heating tube into the expansion chamber. This material flow can be caused either by the movement of the pressure plate or, complementarily or alternatively, by suction. The aforementioned suction can be created by the pressure difference between the expansion chamber and the heating tube upstream of it.

[0088] The shut-off device can, for example, close after a predetermined period. Alternatively, the shut-off device can close after the pressure in the heating pipe drops to a predetermined value.

[0089] After the shut-off device is closed, the pressure in the heating pipe, which is then sealed again in a pressure-tight manner, increases again during the further course of the preferably continuous process, whereupon the shut-off device opens again after the pressure is exceeded or alternatively after a certain time has elapsed as described above.

[0090] It can be assumed that heat transfer in the form of conduction occurs in at least one heating tube, from at least one surface of the heating tube to the plant material. Here, "surfaces of the heating tube" refers to both the tube's casing or sections thereof, as well as, for example, a heating element running inside the tube. Conduction, in this context, refers to heat transfer through mechanical contact, and therefore preferably not through convection or radiation.

[0091] However, convection and / or heat radiation can also be used to heat the plant material, either as an alternative or in addition to the principle of heat conduction.

[0092] The housing of the heating tube can be heated by heating pads that surround the housing. A heating conductor, as mentioned above, is preferably arranged inside the heating tube. Thermal oil, for example, can flow in this heating conductor. Alternative heating methods and variations are conceivable and have already been explained in detail with reference to the fiber digestion device.

[0093] As partially indicated above, the pressure plate, preferably driven by a hydraulic cylinder, determines the material flow direction. Downstream with respect to the material flow direction, the press channel preferably follows the press and dewatering chamber, then the first and optionally the second heating tube, and finally the expansion tank. As also already indicated, the pressure plate is preferably the only device for determining the material flow in the aforementioned components of the fiber digestion apparatus.

[0094] As already described, a further shut-off device, preferably in the form of a second gate valve, is preferably provided between the press and drainage chamber and the press channel. This gate valve is therefore in addition to the gate valve located in the outlet to the pressure relief tank.

[0095] This second slide (or, more generally, the further shut-off device) is preferably closed as soon as it has moved into its position closest to the press channel, where it compacts the plant material, preferably dewaters it, and conveys at least a portion of it into the press channel. After closing, the slide prevents the plant material just conveyed into the press channel from partially flowing back into the pressing and dewatering chamber. Preferably, after the second slide closes, the pressure plate moves against the direction of material flow, whereupon the feed device refills the pressing and dewatering chamber with fresh plant material. The pressure plate then moves in the direction of material flow, compacting and preferably dewatering the plant material.During the aforementioned movement of the pressure plate, the second slide can initially remain closed and act as a stop, counter-bearing, or barrier for the plant material being compacted by the pressure plate. As the pressure plate moves in the direction of material flow, or alternatively, as soon as this movement begins, the second slide opens to allow the plant material to be conveyed into the press channel.

[0096] The second valve can be a hydraulically operated plate valve. This type is typically very low-maintenance. The second valve does not need to be steam- or pressure-tight, which is why it can be very simple in design.

[0097] In light of the foregoing description of preferred variants of the method, it becomes clear that both the feeding device (e.g., the screw conveyor), as well as the pressure plate and the shut-off device (e.g., the slide valve) between the expansion tank and the heating tube immediately upstream of it, are preferably operated intermittently. In contrast, the heating of the heating tubes is preferably continuous.

[0098] The present invention further comprises a method for producing a semi-finished product for the manufacture of paper, cardboard, or carton from a plant material, wherein the plant material is first decongested by steam pressure decongestion according to a variant of the previously described method for decongesting plant material and is subsequently further processed into the semi-finished product. Due to the avoidance of fine particles, which is advantageous in the production of paper and often also of cardboard and carton, the aforementioned method is particularly well suited for the production of paper and preferably also of cardboard and carton.

[0099] Furthermore, the present invention also includes the use of plant material treated according to a previously described method for the production of paper, cardboard or carton, or for the production of a semi-finished product which is used in the production of paper, cardboard or carton. Character description

[0100] Further advantages, features and details of the invention will become apparent from the following description of preferred embodiments and from the drawings; these show in: Fig. 1 a sectional view of a fiber extraction device 1, in Fig. 2 a sectional view along line II-II in Fig. 1, as well as in the Fig. 3, Fig. 4 to Fig. 5 different views of a press 32. Example of implementation

[0101] In Fig. Figure 1 shows a fiber pulping device 1 for pulping plant material by means of steam pressure pulping. The device 1 comprises, in this order, a pressing and dewatering chamber 2, a pressing channel 3, a first heating tube 4, a second heating tube 5, and a pressure relief tank 6. The aforementioned components 2, 3, 4, 5, 6 are designed as zones of the fiber pulping device 1.

[0102] A pressure plate 9, driven by a hydraulic cylinder 11, is associated with the pressing and dewatering chamber 2. A feed device 7 in the form of a screw conveyor 7 is also associated with the pressing and dewatering chamber 2. Furthermore, a perforation 8, formed by numerous adjacent bores, can be seen in a housing 27.2 of the pressing and dewatering chamber 2. The perforation 8 is located on a housing section 14.2 of the housing 27.2 of the pressing and dewatering chamber 2 between an inlet 19 and a transition to the pressing channel 3.

[0103] In the press channel 3, backflow prevention devices 10 are visible, only some of which are labeled with reference numerals. In the enlarged section A, a wedge-shaped cross-section of the backflow prevention device 10 is visible. It has a sliding surface 25 and a stop surface 26. The sliding surface 25 is arranged such that the distance (not shown) between the sliding surface 25 and a central longitudinal axis 28 (indicated only) decreases along a material flow direction.

[0104] Heating pipe inserts 12.4 and 12.5 are visible inside the heating pipes 4 and 5. Heating pads 13.4 and 13.5 are also arranged outside the heating pipe housings 27.4 and 27.5.

[0105] A shut-off device in the form of a gate valve 15 is visible at a transition between the second heating pipe 5 and the expansion tank 6. Furthermore, a discharge screw 16 is arranged at the bottom of the expansion tank 6.

[0106] In Fig. Figure 2 shows a heating pad 13.4, the housing 27.4 of the first heating tube 4, and the heating tube insert 12.4 with four brackets 20.4. A clear dimension 23.4 of the first heating tube 4 is shown in Fig. 2 noted. Furthermore, the heating pipe insert 12.4 includes a heating line 30.4 arranged centrally in the first heating pipe 4.

[0107] The Fig. 3, Fig. 4 to Fig. Figure 5 shows various views of a press 32, which can be used in place of the pressure relief tank 6. A press table 33, a guide 34, a shot line 35, a hydraulic cylinder 36, a punch-bearing cylinder 37, a press housing 38, a steam outlet pipe 18.1, and a discharge screw 16.1 are visible. With reference to Figures 1 to 5, the functioning of the device according to the invention and the method according to the invention are explained as follows:

[0108] The plant material to be processed is fed into the pressing and dewatering chamber 2 via the screw conveyor 7, along the conveying direction 21, i.e., following gravity. The pressure plate 9, driven by the hydraulic cylinder 11, then moves the plant material in the material flow direction 24. Fig. 1 also to the right, in the direction of the press channel 3. Preferably at the beginning of this movement of the pressure plate 9, the second slide 31 is moved into the raised position, which in Fig. Figure 1 shows the connection between the pressing and dewatering chamber 2 and the pressing channel 3 in this raised position. As the pressure plate 9 moves to the right, the plant material accumulates in the pressing channel 3, forming the plug described in more detail below. Since this plug offers some resistance to the plant material being conveyed by the pressure plate 9 in the material flow direction 24, dewatering occurs in housing section 14.2 of the housing 27.2 of the pressing and dewatering chamber 2. Specifically, this dewatering takes place when the pressure plate 9 compresses the plant material in housing section 14.2, causing the plant material to partially dewater through the perforation 8.

[0109] The partially dewatered plant material is immediately introduced into the press channel 3 by the movement of the pressure plate 9 and compressed there into a plug. If the second slide 31 is opened to the right at the beginning of the movement of the pressure plate 9, which is preferred, the plant material is compressed and dewatered in the press and dewatering chamber 2 and introduced into the press channel 3 simultaneously.

[0110] Since the movement of the plant material described above is effected by the pressure plate 9, and not by a screw conveyor or the like, fewer fine particles are produced during the material flow and compaction due to the lower friction and shear. This has a particularly positive effect on paper or similar products that can be made from the plant material.

[0111] The fiber extraction device 1 is operated continuously, i.e., the hydraulic cylinder 11 moves the pressure plate 9 back and forth continuously. In addition, plant material is fed either continuously or periodically into the pressing and dewatering chamber 2 via the screw conveyor 7, which is then conveyed by the pressure plate 9 to the press channel 3 in the material flow direction 24.

[0112] It may be possible to coordinate the operation of the screw conveyor 7 with a movement of the pressure plate 9. For example, it may be possible to configure the screw conveyor 7 to only convey plant material when the pressure plate 9 is in its "fully left" position, i.e., in the position shown in the diagram. Fig. 1 is in the withdrawn position shown; or as long as the pressure plate 9 is in the material flow direction 24 in front of an inlet 19 (in Fig. 1 also “to the left of the inlet 19”), which connects the screw conveyor 7 with the press and dewatering chamber 2.

[0113] Furthermore, the raising and lowering of the second slide 31 can be coordinated with the aforementioned movements. For example, the second slide 31 can be raised as soon as the pressure plate 9 begins to move to the right. The second slide 31 can be lowered as soon as the pressure plate 9 is in its maximum rightward deflection position. In this way, the second slide 31 prevents plant material from the press channel 3 from migrating into the press and dewatering chamber 2 against the material flow direction 24 before the press and dewatering chamber 2 is filled by the screw conveyor 7.

[0114] The back-and-forth movement of the printing plate 9 takes place along or against the material flow direction 24.

[0115] The back-and-forth movement of the hydraulic cylinder 11, and thus of the pressure plate 9, occurs parallel to the movement described in Fig. 1 only indicated common central longitudinal axis 28 of hydraulic cylinder 11, pressure plate 9, press and drainage chamber 2, press channel 3, first and second heating tubes 4, 5 and the heating tube inserts 12.4, 12.5. The aforementioned components 11, 9, 2, 3, 4, 5, 12.4, 12.5 are thus arranged coaxially to each other.

[0116] Due to the continuous operation, plant material is continuously fed from the pressing and dewatering chamber 2 into the pressing channel 3. Plug formation in the pressing channel 3 occurs partly due to the compression of the plant material by the pressure plate 9. Plug formation is also supported by the design of the pressing channel 3.

[0117] The cross-sectional representation according to Fig. The backflow prevention devices 10, which are clearly visible in section A and 1, act similarly to a ratchet mechanism with respect to the plant material conveyed in the material flow direction 24: The sliding surface 25 is inclined at an angle of less than 45° to the material flow direction 24 and allows the plant material to be conveyed in this direction. The plant material slides along the sliding surface 25. The stop surfaces 26, which are perpendicular to the material flow direction 24, prevent the plant material from moving in the opposite direction. This prevents the plant material from "falling back to the left" (with respect to the material flow direction 24). Fig. 1) of the plant material in the press channel 3 is avoided, even when the pressure plate 9 moves in the opposite direction after the maximum deflection of the hydraulic cylinder 11 in the material flow direction 24. Fig. 1, also moved to the left.

[0118] Due to the movement of the pressure plate 9, which continuously introduces new plant material into the press channel 3 in the material flow direction 24, a portion of the plant material pressed into the plug constantly passes into the first heating tube 4 at the transition between the press channel 3 and the first heating tube 4. There, the plant material is heated by means of a heating pad 13.4 and a heating tube insert 12.4. The cross-sectional areas of the press channel 3 and the first heating tube 4 are selected such that both are essentially completely filled with plant material during operation. The second heating tube 5 has a larger cross-sectional area compared to the first heating tube 4, which is why the fill level of the second heating tube 5 is significantly less than 100% during operation. This will be explained in more detail below.

[0119] The fill level of the press channel 3 and the first heating tube 4 is preferably 100% during operation. "During operation" here preferably means a continuous operation of the fiber processing device 1, wherein the plug in the press channel 3 has already been installed, and wherein plant material has already entered the expansion tank 6 via the outlet 29.

[0120] During operation, the movement of the pressure plate 9 within the pressing and dewatering chamber 2 serves to generate a fill level of 100% in the pressing channel 3, which is why the fill level in the pressing and dewatering chamber 2 is usually less than 100%. Due to the periodic back-and-forth movement of the pressure plate 9 and the introduction of plant material by the screw conveyor 7, the fill level in the pressing and dewatering chamber 2 typically changes continuously.

[0121] Since it has a larger internal diameter 23 compared to the first heating tube 4, and regularly discharges plant material via the outlet 29 to the expansion tank 6, the second heating tube 5 is preferably not 100% full during operation. Often, a gradient in the fill level develops in the second heating tube 5, with the fill level decreasing towards the outlet 29, based on a cross-sectional area of ​​the second heating tube 5 running orthogonally to the central longitudinal axis 28.

[0122] The plant material, which was conveyed into the second heating tube 5, is further heated there by means of the heating tube insert 12.5 and the heating pads 13.5.

[0123] The heating in the heating tubes 4 and 5 leads to a pressure increase. Depending on the pressure, i.e., particularly when a predetermined pressure is reached, the slide valve 15 of an outlet 29 opens, which connects the second heating tube 5 to the expansion vessel 6. The pressure in the expansion vessel 6 is significantly lower than the pressure that existed in the heating tubes 4 and 5 immediately before the slide valve 15 opened. This pressure drop causes the water contained in the plant material to evaporate explosively, resulting in steam pressure digestion.

[0124] An interior space of the expansion vessel 6 can be connected via a steam outlet pipe 18 to a downstream device in which the discharged steam is condensed and / or otherwise used. Furthermore, a pipe 17 with a rupture disc is provided, which replaces the steam outlet pipe 18 should the latter become blocked. If the steam outlet pipe 18 is blocked, the pipe 17 with the rupture disc can reliably prevent a dangerous pressure increase by rupturing the rupture disc and creating pressure equalization. It is also possible to arrange a safety valve in the pipe 17 downstream of the rupture disc, so that the rupture disc is connected to the interior space of the expansion vessel 6.

[0125] The processed plant material is conveyed out of the relaxation tank 6 by means of the discharge screw 16. The processed plant material can then be further processed.

[0126] For heating in the heating tubes 4, 5, in addition to the heating pads 13.4, 13.5 for heating the housing 27.4, 27.5, a heating line 30.4, 30.5 is preferably provided inside each of the heating tubes 4, 5. This heating line 30.4, 30.5 is each part of a heating tube insert 12.4, 12.5. The heating tube inserts 12.4, 12.5 include the cross-shaped brackets 20.4, 20.5, which secure the heating lines 30.4, 30.5 inside the heating tube 4, 5. Thermal oil flows through the heating lines 30.4, 30.5.

[0127] During the relaxation container 6 according to Fig. While press 1 essentially provides an enclosed cavity for steam pressure digestion within its interior, press 32 offers the possibility of performing solid-liquid separation in addition to steam pressure digestion. The components in the Fig. 3, Fig. 4 to Fig. The press 32 shown in section 5 can replace the relaxation container 6.

[0128] The firing line 35 of the press 32 takes over the function of the outlet 29 in this process. Fig. 1. The firing line 35 comprises a (in the Fig. 3, Fig. 4 to Fig. 5 (not shown or not recognizable) slides or the like, whose function is already evident with regard to slide 15 in Fig. 1 was explained.

[0129] Preferably, the press housing 38 is sufficiently thick-walled to act as a baffle plate with respect to the plant material, which typically enters the press housing 38 at high speed through the shot tube 35. When the plant material enters through the shot tube 35, the ram-carrying cylinder 37 is in its upper end position. A (in the Fig. 3, Fig. 4 to Fig. 5 (not recognizable) plunger, which closes the press housing 38 at the top, moves after the plant material has entered and the shot tube has been closed by means of the (into the Fig. 3, Fig. 4 to Fig. 5 (not shown) slide downwards towards discharge screw 16.1. Here, the plant material located in the press housing 38 is compressed and liquid components are squeezed out. The squeezed-out liquid can be applied to suitable (and in the Fig. 3, Fig. 4 to Fig. 5 (not shown) removed in the manner known from presses of the prior art.

[0130] The press table 33 and the discharge screw 16.1 are linearly movable on the guide 34 in the form of a slide. Fig. 4. The aforementioned components, which are preferably combined into an assembly, can thus be moved from left to right with the aid of the hydraulic cylinder 36. The aforementioned assembly, together with the guide, therefore forms a - in Fig. 4 linear guides movable to the right and left.

[0131] After the (not shown) punch has been moved from the punch-carrying cylinder to its lower end position, the aforementioned assembly (with regard to Fig. 4) The press is moved to the right so that, instead of the press table 33, the discharge screw 16.1 is arranged directly below the press housing 38. After the ram is lowered and the solid-liquid separation occurs, a press cake consisting of the deconstructed plant material is present inside the press housing 38. Water and liquefied lignin were preferably removed during pressing. A suitable device for removing liquids can be used for this purpose in such presses, which is not shown separately in the drawings.

[0132] Starting from the previously reached lower end position, the (not shown) piston can now be lowered further slowly and with a light load using the piston-bearing hydraulic cylinder 37, while the discharge screw 16.1 simultaneously "mills off" the press cake that has been carefully pushed down in this way.

[0133] Although only some preferred embodiments of the invention have been described and illustrated, it is obvious that the person skilled in the art can add numerous modifications without departing from the essence and scope of the invention. In particular, the following modifications may be considered:

[0134] Thermal insulation can be arranged at a transition between the press channel 3 and the first heating tube 4, where the housing 27.3 of the press channel and the housing 27.4 of the first heating tube 4 touch. This insulation can prevent heat, which is generated, for example, by the heating pads 13.4 and is intended to be transferred to the plant material inside the first heating tube 4, from heating the housing 27.3 of the press channel 3 and the plant material inside the press channel 3. The primary purpose of the press channel 3 is to form the plug, and excessive heating of the plant material is generally detrimental to this process.

[0135] Although this in Fig. Figure 2 shows only the first heating pipe 4; the press and drainage chamber 2, the press channel, and also the second heating pipe 5 have an essentially cylindrical shape. The aforementioned components are therefore, in cross-section, i.e., orthogonal to the central longitudinal axis 28, just like the first heating pipe 4 (see Figure 2). Fig. 2) round.

[0136] The sliding surfaces 25 can have an angle of preferably less than 60°, more preferably less than 45°, and even more preferably less than 30° to the central longitudinal axis 28. The stop surface 26, on the other hand, is preferably arranged substantially orthogonally to the central longitudinal axis 28.

[0137] The clear dimension 23.4 of the first heating pipe 4, as well as all other (not shown) clear dimensions of the adjacent components, which are essentially coaxial to each other, are measured orthogonally to the central longitudinal axis 28.

[0138] A safety valve can be installed in the second heating pipe 5. To protect this safety valve from contamination by plant material, a rupture disc can be installed upstream of the safety valve.

[0139] Should this safety valve (not shown in the drawings) in the second heating tube 5, as well as both the tube 17 with rupture disc and the steam outlet tube 18, be blocked or unable for any reason to reduce excessive pressure within the heating tubes 4, 5 and the expansion tank 6, the plug in the press channel 3 would burst and the excess pressure would escape through the perforation 8 in the press and drain chamber 2. While this is undesirable, it provides protection against more serious machine and / or personal injury in the event that the aforementioned "regular" pressure reduction devices fail. A baffle plate or similar device surrounding the perforation 8 is therefore advisable.

[0140] In addition to or as an alternative to the perforation 8, the water can also escape via a perforation (not shown) in the pressure plate 9 or via the gap between the pressure plate and the inside of the press and drain chamber 2. Preferably, the pressure plate 9 is not sealed against the inner wall of the housing 27.2 of the press and drain chamber 2, for example by a ring seal.

[0141] Within the expansion chamber 6, a grid (not shown) can be arranged such that the plant material entering the expansion chamber 6 from the second heating tube 5 via the outlet 29 directly impacts the grid and is shredded by this impact. Instead of the grid, any alternative shredding device can be used, preferably passive shredding devices such as statically arranged blades or the like, which are just as suitable as the grid for shredding the plant material. The grid or an alternative shredding device can also be arranged within the outlet 29.

[0142] The brackets 20 may be designed differently than is particularly evident in Fig. Figure 2 shows that the cross-shaped arrangement is not essential. The heating cables 30.4, 30.5 can also be held by a different number of brackets 20.4, 20.5.

[0143] It may be possible to accomplish the heating in one or both heating tubes 4, 5 either exclusively by means of the heating pads 13.4, 13.5, or exclusively by means of the heating tube inserts 12.4, 12.5, which preferably each comprise a heating line 30.4, 30.5.

[0144] If the heating pads 13.4, 13.5 are omitted, the housing 27.4, 27.5 of the heating tube 4, 5 can be thermally insulated particularly effectively. If all heating tube inserts 12.4, 12.5 are omitted, there are no components inside the heating tubes 4, 5 where an unwanted build-up of plant material could occur.

[0145] Despite the aforementioned potential disadvantages, the advantages of heating pads 13.4, 13.5 and heating tube inserts 12.4, 12.5 outweigh the disadvantages, which is why both are preferably used.

[0146] Instead of the heating pads 13.4, 13.5, alternative heating devices can be used to heat the housings 27.4, 27.5.

[0147] Instead of the heating pipes 30.4, 30.5, alternative heating devices can also be considered within the heating pipes 4, 5.

[0148] This can always include heat transfer devices based on the principles of thermal radiation or convection. For example, it is conceivable to introduce hot steam into the second heating tube 5 via a suitable device (not shown) in order to heat the plant material located there. This can be considered as an alternative or in addition to the heating pads 13 and the heating tube insert 12.

[0149] Instead of the screw conveyor 7, a different feeding device can be used.

[0150] Instead of press 32, other solid-liquid separation devices may be used. These may either be located in the relaxation vessel 6 or replace it. Reference symbol list 1 Fiber Discharge Device 2 Pressing and drainage chambers 3 Press channel 4 first heating pipe 5 second heating pipe 6 relaxation containers 7 Feeding device / screw conveyor 8 Perforation 9 Printing plate 10 Backflow prevention device 11 hydraulic cylinders 12 Heating pipe insert 13 heating pads 14 Housing section 15 Shut-off device / gate valve 16 discharge auger 17 Pipe with burst disc 18 Steam outlet pipe 19 Admission 20 Brackets for heating pipe inserts 21 Direction of conveyance of the screw conveyor 22 Direction of action of gravity 23 Clear measure 24 Material flow direction between press and dewatering chamber and pressure relief tank 25 sliding surface 26 Stop surface 27 cases 28 Central longitudinal axis 29 Outlet 30 heating pipes 31 second slider 32 Press 33 Press table 34 Leadership 35 shot line 36 hydraulic cylinders 37 Stamp-bearing cylinder 38 press housings

Claims

[1] Fiber digestion device (1) for digesting plant material by steam pressure digestion, the device comprising a press and drain chamber (2), a press channel (3), at least one first heating tube (4), and a pressure relief tank (6), wherein the pressing and dewatering chamber (2) is associated with a pressure plate (9) for compacting and dewatering the plant material and for determining a material flow in the fiber extraction device (1), wherein the pressing and dewatering chamber (2) is further connected with a feeding device (7) for feeding the plant material to be processed, wherein the pressing and dewatering chamber (2), the pressing channel (3), the at least one first heating tube (4), and the pressure relief tank (6) are connected to each other in such a way that plant material introduced into the pressing and dewatering chamber (2) by the feeding device (7) is first moved into the pressing channel (3) by a movement of the pressure plate (9) and then passes through the at least first heating tube (4) in order to then enter the pressure relief tank (6). [2] Fiber extraction device (1) according to claim 1, characterized by at least a backflow prevention device (10) in the press channel (3) and / or a perforation (8) in at least one section (14.2) of the press and drainage chamber (2). [3] Fiber extraction device (1) according to any one of the preceding claims, characterized bya second heating tube (5) which is arranged between the first heating tube (4) and the expansion vessel (6), wherein a clear dimension of the second heating tube (5) is larger than a clear dimension of the first heating tube (4). [4] Fiber extraction device (1) according to at least one of the preceding claims, characterized by , that the clear dimension of the first heating pipe (4) is smaller than a clear dimension of the press channel (3). [5] Fiber extraction device (1) according to at least claim 3, characterized by a shut-off device (15) at the transition between the second heating pipe (5) and the expansion tank (6). [6] Fiber extraction device (1) according to at least one of the preceding claims, characterized by a thermal insulation between a housing (27.3) of the press channel (3) and a housing (27.4) of the first heating tube (4). [7] Fiber extraction device (1) according to at least one of the preceding claims, characterized by, that the feeding device (7) is a screw conveyor (7). [8] Method for digesting plant material by means of steam pressure digestion using a fiber digestion device (1) according to any one of claims 1 to 7, wherein the plant material is fed into the pressing and dewatering chamber (2) via the feeding device (7), wherein the plant material is subsequently compacted and preferably at least partially dewatered by a movement of the pressure plate (9) in the pressing and dewatering chamber (2), the plant material is then introduced into the press channel (3) by the movement of the pressure plate (9) and pressed there into a plug, wherein the plant material subsequently leaves the press channel (3) and is conveyed into at least one first heating tube (4) and heated there, which leads to a pressure increase in at least one first heating tube (4), wherein the plant material subsequently leaves the at least one first heating tube (4) and enters the expansion vessel (6), in which a lower pressure prevails compared to the at least one first heating tube (4), and wherein the plant material is broken down during entry into the expansion vessel (6). [9] Method according to claim 8, wherein a material flow direction of the plant material within the fiber extraction device (1) between the pressing and dewatering chamber (2) and the end of the first heating tube after the introduction of the plant material through the feeding device (7) is determined solely by the pressure plate (9). [10] Method according to one of claims 8 or 9, characterized by that the process runs continuously. [11] Method according to any one of claims 8 to 10, characterized in that the temperature inside the at least one first heating tube (4) is at least 125°C, preferably at least 130°C, and / or the dry matter content of the plant material immediately before entering the relaxation container (6) is between 28 and 40%. [12] Method according to any one of claims 8 to 11, characterized by , that the shut-off device (15) opens depending on the pressure prevailing in at least one heating pipe (4, 5). [13] Method according to at least one of claims 8 to 12, characterized by , that in the at least one first heating tube (4) a heat transfer in the form of heat conduction takes place from at least one surface of the at least one first heating tube (4) to the plant material. [14] Method for producing a semi-finished product for the production of paper, cardboard or carton from a plant material, wherein the plant material is first decongested according to one of claims 8 to 13 and then further processed to form the semi-finished product. [15] Use of plant material treated according to a method according to at least one of claims 8 to 13 for the production of paper, cardboard or carton or for the production of a semi-finished product which is used in the production of paper, cardboard or carton.

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